AMX NI-3101-SIG manual Dddp, Be polled for devices

NetLinx Security within the Web Server

Polling:	• Dynamic physical devices can be detected by DDDP through both Serial and IP
	interfaces.
	• While IP connections are then able to utilize the LAN’s higher layers of multicast to
	broadcast their existence, Serial devices speak a fixed protocol that is incompatible with
	DDDP.
	• Serial devices are passive and will only broadcast their existence if polled to do so. The
	program developer must specify which NetLinx interfaces/ports (i.e. serial ports) should
	be polled for devices.

What is the difference between Program and Run-time defined binding?

In DDD, the device discovery activity is always dynamic because the devices will always be detected at run- time. Note that DDD splits the binding activity into two different categories:

Program defined binding (also known as static) Run-time defined binding (also known as dynamic).

With program defined/static binding, the developer specifies a permanent binding between an application device and a physical port, such as a particular serial or IR port. At run-time, any device detected on that port is automatically associated with the designated application device. This binding type would be used when the developer wants to hard code what port is used for a device, but does not know what manufacturer's device will actually be connected. Static binding is not available for IP connected devices, since the IP Address value of a device is subject to change due to IP LAN topology.

An example of its use would be if DHCP is enabled for the peripheral device. A

hard-coded IP Address within the NetLinx "glue-code" would be inadequate due to the nature of the dynamically acquired DHCP IP Addresses. Only actual NetLinx D:P:S values are allowed for static binding of physical ports.

With run-time defined/dynamic binding, the application device and the physical port are completely disassociated (in a program sense). The developer defines the application devices and their associated SDK class but does not specify what physical port they are bound to. At run-time, as those devices are discovered, the new physical devices are then bound to an application device either automatically or via the Master's Web access. Dynamic binding is the only binding option available for IP-connected peripheral devices due to the dynamic nature of IP Addresses as discussed earlier.

84 NI-3101-SIG Signature Series NetLinx Integrated Controller